As a key component of an LCD device, a backlight module is mainly used for providing sufficient brightness and uniformly distributed light sources, to enable an LCD device to normally display images
FIG. 1 shows a backlight module of an LCD device, including a backplane 100, a lightbar 140 fixed on the side wall of the backplane 100, a reflecting plate 110 arranged on the backplane 100, a light guide panel (LGP) 120 which is arranged on the reflecting plate 110 and opposite to the lightbar 140, a rubber frame 150 and an outer frame 200 which are arranged outside the backplane 100 and used for pressing the LGP 120; optical film(s) 130 is arranged on the light emitting surface of the LGP 120, and an LCD panel 300 is fixed above the backlight module by components including the rubber frame 150, the outer frame 200 and the like. Because the lightbar 140 of such structure is fixed on the backplane 100, in an inner cavity of the backlight module, heat emitted by the lightbar 140 is conducted to the surface of the backplane 100 through the side wall of the backplane 100 and then dissipated through air convection. However, because the heat conduction path is long, the heat is accumulated in the inner cavity of the backlight module for a long time, resulting in certain damage to the components in the backlight module; thus, the components such as the reflecting plate 110, the LGP 120 and the like in the backlight module operate in an area of accumulated heat for a long time and then change, affecting the stability and the service life of the components in the backlight module, and the stability of the LCD panel, and then reducing the display effect of the LCD device.
In addition, as shown in FIG. 2, the lightbar 140 mainly includes an LED 141 and a printed circuit board (PCB) 142; the LED 141 is a light source and generates a lot of heat when emitting light. The heat is conducted to the backplane 100 through the PCB 142 and to an aluminum extrusion (not shown in the Figure) arranged on the back side of the PCB as well, and then conducted out through the backplane 100. The PCB is not a good heat conductor because of the material reason thereof. Thus, most of heat is accumulated on the lightbar 140 for a long time, and the inside temperature of the cavity of the lightbar 140 is high for a long time, thereby affecting the safety and the service life of the components in the backlight module and the LED, and then reducing the optical quality of the backlight module if the components in the backlight module are affected.
As shown in FIG. 3, U.S. Pat. Pub. No. US2010/0002418A1 discloses another backlight module, including a backplane 100, a heat conducting plate 190 closely attached to the backplane 100, a lightbar 140 fixed on the side wall of the backplane 100, an LGP 120 arranged opposite to the LED 141 on the lightbar 140, a reflecting plate 110 arranged below the LGP 120, and an outer frame 200 arranged outside the backplane 100; optical film(s) 130 is arranged on the light emitting surface of the LGP 120, and an LCD panel 300 is arranged above the backlight module. In addition, the backlight module further includes a support piece 170 which is used for supporting the reflecting plate 110 and the LGP 120 thereon; thus, an air cavity 180 is formed between the heat conducting plate 190 and the reflecting plate 110, to play a role of heat insulation. The lightbar of the backlight module of such structure includes a PCB and an LED 141; the PCB is arranged on the backplane 100 or the aluminum extrusion. However, although the influence of the heat on the reflecting plate 110, etc. is avoided during heat transfer as far as possible in the arranging mode, the heat conduction path remains that: heat is conducted to the backplane 100 through the heat conducting plate 190, and is dissipated through the contact between the backplane 100 and air. Because the heat conduction path is still long, heat is accumulated inside the backlight module for a long time, thereby affecting the service life and safety of the components in the backlight module, and the service life of the LCD panel of the LCD device.